Silver halide emulsions



3,165,412 SELVER HALIDE EMULSEONS Louis M. Minsk and Edward P. Abel, both of Rochester, N.Y., assignors to Eastman Kodak Company, Roche. ester, N.Y., a corporation of New ,llersey No Drawing. lFiied Sept. 18, 1961, Ser. No. 138,627

8 Claims. (6!. 96-114) This invention relates to the use in gelatin-silver halide photographic emulsions of gelatin-compatible polyvinyl alcohol derivatives which beneficially influence the density of the developed silver image. I

The maximum optical density of the silver image of a photographic film after exposure, wet processing and dry ing and hence the covering power appears to depend not only upon the amount of silver which results from the development process, but also upon the Way the silver is laid down in the photographic element during processing and the stresses to which it is subjected in the drying step. The term covering power as used herein refers to the ratio of the optical density of the developed silver to the actual quantity of silver.

\iiue'nced during the processing and drying by the vehicle in which the silver halide grains are suspended. For instance, the vehicle may restrict expansion of filamentary masses of silver produced in the photographic development process. The development of silver halide grains into filaments of metallic silver is explained in Mees, C. E. K., The Theory of the Photographic Process, revised edition, 1954, pp. 508, 509. The changes in density and covering power which take place during drying probably result primarily from changes in the spacing and orientation of individual filaments as a result of the drying down of the colloid vehicle.

We have found that the partial replacement of the gelatin of a photographic emulsion with a polyvinyl alcohol half ester of an aliphatic dicarboxylic acid increases the covering power of the developed silver. This is particularly true of coarse-grained emulsions such as gelatinsilver bromoiodide photographic emulsions. When a substantial proportion of the gelatin, up to 30%, has been replaced with a poly(vinyl alcohol) half ester of an aliphatic dicarboxylic acid there is an increase in covering power by as much as 27% over that of the silver in control coatings.

The increase of density by the use of a poly(vinyl alco hol) half ester of an aliphatic dicarboxylic acid has been found in photographic emulsions having various rations of gelatin to half ester. Our invention relates to silver halide photographic emulsions in which from 10 to 30 weight percent of the carrier for the silver halide is composed of a poly(vinyl alcohol) half ester of an aliphatic dicarboxylic acid. Emulsions containing such proportions of poly(vinyl alcohol) half esters of an aliphatic dicarboxylic acid give increased covering power and hence higher contrast, speed and maximum density than do corresponding coatings in which gelatin is the sole carrier for the silver halide.

A number of similar additives have been used in photographic emulsions for other purposes, e.g.', for increasing the flexibility of photographic films, increasing coating viscosity, etc. Many of these leach out of the gelatin layer during processing and most are Without particular photographic effect.

The polyvinyl phthalates of Hiatt et al., US. Patent 2,759,909, issued August 21, 1956, are disclosed in Weyerts et al., US. Patent 2,218,255, issued October 15,

1940, as useful for increasing the viscosity of gelatin solutions but are stated .tohave no influence on photographic United States PatentO properties, which would be expected, these not being halfesters nor are they esters of aliphatic dicarboxylic acids. Weyerts et a1. points out that the presence of silver halide is not necessary to obtain the viscosity effect.

The Illingworth and Minsk US. application Serial No. 700,555, filed December 4, 1957, describes the use of carboxyl derivatives of hydroxyethyl cellulose in admixture with gelatin colloid in photographic emulsions to decrease the image density loss that takes place on drying. The polyvinyl alcohol half esters of aliphatic dicarboxylic acid of our invention give substantially greater increases in density, speed and contrast than do the cellulose derivatives of US. Serial No. 700,555.

Our invention is particularly directed to the incorporation of water-soluble poly(vinyl alcohol) half esters of aliphatic dicarboxylic acids in gelatin-silver halide photographic emulsion compositions in which the silver halide is, for example, silver chloride, silver bromoiodide, or the like. The compositions of our invention are prepared by mixing aqueous gelatin compositions with the Watersoluble half esters in a proportion which gives a composition having the desired properties. When the polyvinyl alcohol half esters of aliphatic dicarboxylic acid composition are added to a photographic gelatin silver halide emulsion and coated on a suitable support, the composition is resistant to leaching out during photographic processing and is able to contribute its effect during and after processing.

It is an object of our invention to provide gelatin photographic emulsion compositions which exhibit an increase in covering power of the developed silver thereof, particularly high speed negative emulsions.

Another object of our invention is to prepare suc emulsions without adverse effect on other sensitometric characteristics such as the fog, density, resolution, and acutance, and without adverse effect on physical characteristics such as flexibility and clarity of the coated layer. Other objects of our invention will appear herein.

We have realized these objects by the addition to a photographic silver halide emulsion of a poly(vinyl alcohol) half ester of an aliphatic dicarboxylic acid, the dicarboxylic acid having a carbon chain length of 2 to 7 carbon atoms reacted with a poly(vinyl alcohol) to the extend of between 7.0 and 90 mole percent. By a poly (vinyl alcohol) we mean poly(viny1 acetate) that has been hydrolyzed to about 50 to 100 mole percent poly(vinyl alcohol) with the preferred range of poly(vinyl alcohol) being from about to 1-00 mole percent.

The poly(vinyl alcohol) half esters of an aliphatic dicarboxylic acid of our invention fall within the following general formula:

[( r x F 1);- 2 D 1] Poly(vinyl alcohol) 10-93 mole percent Poly(viny1 alcohol) acid ester=7.0- mole percent Poly(vinyl acetate)=0-50 mole percent The following examples illustrate the making of the half esters and their use as addenda to photographic emulsions.

EXAMPLE 1.-COPOLY(VII-IYL ALCOHOL-VINYL ACID SUCCINATE) In a 300 ml. flask, equipped with a reflux condenser, thermometer, and mechanical stirring, were placed 110 ml. of distilled dimethyl formamide (DMF) and 22 g. of'low viscosity poly(vinyl alcohol) (PVA) Whichis essentially completelyhydrolyzed. The suspensionnwas heated on'a Glas-Col mantle to 135 F. with stirring. A brown, clear dope was obtained. To this, at 145 C.,' was added succinic anhydride (in the amounts given below), and the solution was heated for /4 hour at 145- 149 C. The dope was diluted'with approximately an equal volume of dimethyl forrnarnide, cooled and was poured, in a fine stream, into stirred acetone. The prodnot which precipitated was washed in fresh acetone several times and dried in a desiccator under a constantly applied water pump vacuum at room temperature. Pertinent data .are given in Tables I and II. V

Table I Mole Percent; Ompd. PVA DMF Sucoinlc Reaction No. (54.) (mL) Anhy- Yield Solubility dride (g) 0210. Found 1 22 110 5 17 7.65 Water/room temp. 2 22 110 10 21 20 14.2 D0. 3 22 110 24 30 21.5 D0. 4.; 22 110 28 40 26.2 \Vater-l- Alkali. 5 22 110 55 35 100 80.5 D0.

Samples of a coarse-grained gelatino-silver bromoiodide emulsion containing the normal emulsion addenda, e.g., spreading agents, hardeners, etc, and 178g. gelatin per mole of silver halide, and, in addition, the above compounds were coated and dried. A fresh strip of each coating was exposed in an Eastman lb sensitometer, de-' veloped for 3 minutes in Kodak D19!) Developer, fixed, washed and dried. The results obtained are tabulated below.

The following procedure is preferred for putting the 'succinoylated polyvinyl alcohol into solution, thereby preparing it for use with a photographic silver halide emulsion:

In a 3-liter beaker, immersed in an ice water bath, were placed 1300 ml. of cold distilled water. With vigorous mechanical stirring 350 g. of dried succinoylated poly- (vinyl alcohol) were added gradually. Stirring and chilling were continued until doping was complete. If neces sary, as indicated in Table l, 10% sodium hydroxide was added slowly, keeping the pH below 6.5 Doping took about 9 hours. The dope was refrigerated overnight-and the following morning the cold. dope was strained, through cheesecloth to remove any undissolved particles. Again if necessary with vigorous stirring and cooling, cold 10% aqueous sodium hydroxide was added slowly through a burette until the pH was adjusted to 6.5, as read by a Beckman Model G pH meter. The dope was stored. in a refrigerator. A solid content was determined by drying a sample at 100 C. for 16 hours. Asample of the cold dope was acidified with cold aqueous 12% HBr and iso- Titration showed that very little hydrolysis had occurred.

EXAMPLE 2.-COPOLY(VINYL ALCOHOL-VINYL ACID SUCCTNATE) In a 5-liter flask, equipped with a reflux condenser, stirrer and thermometer, were placed 2500 ml. d'irnethyla formamide (EK Co. No. 5870) and 660 g. low viscosity poly(vinyl alcohol) (DuPont Elvanol RH 393) which is essentially completely hydrolyzed. The stirred suspension was heated to 135 Coon a Glas-Col mantle qto ob: tain a clear, light amber dope. "At this temperature, a

tion in 1:1 pyridine-water (200 ml./ g.) with N/ 10 NaOI-l' to a phenol-phthalein end point indicated a combined vinyl acid succina.e content of 23.6 mole percent.

The copolymer appears to be permanently stable in solution, when it is dissolved and stored as'directed in Example 1. I

ACETATE-VINYL ACID SUCCINATE) In a 500 ml. flask equipped with a reflux condenser, stirrer and thermometer were placed 220 ml. pyridine (EK Co. 214) and 44 g. of incompletely hydrolized poly (vinyl acetate) (88 mole percent vinyl alcohol-Elvanol 51-05). The suspension was heated with stirring in a steam bath to C. when 40 g. of succinic anhydride (BK Co. 868) were added. The heating and stirring were continued for 2 hours during which time the temperature rose to a high of 106 C; and dropped to '9596 C. and doping occurred. The dope was cooled to 55 C. by a stream of cold tap water, diluted with ml. acetone, and precipitated by pour-ing into stirred acetone. The soft cake was extracted repeatedlywith fresh changes of acetone. It was then dried in a vacuum oven at room temperature under a constantly apphedwater pump vacuum. Titration of the polymer indicated a carboxyl content equivalent to 4.06 ml. N alkali/ g.

The procedure in Example 1 was used to get the copolymer into solution.

EXAMPLE 4.COPOLY(VINYL ALCOHOL-VINYL ACID SUCCINATE In a 3 liter fiaskequipped with a reflux condenser, stirrer and thermometer were placed 1200 .ml. dimethylformamide (EK Co. 5870) and 264 g. of poly(vinyl alcohol), Elvanol 70-05, which is essentially completely hydrolyzed. The suspension was stirred and heated in a steam bath Whll 240 g. succinic anhydride (EK Co. 868) followedby ml. of pyridine (EK Co. 214) were added. In about 15 minutes the slurry became a light tan dope. The heating and stirring were continued for a total of 1% hours. The dope was cooled to 50 C., diluted with 200 ml. of dime ylfo'rmamide and precipitated by pouring into 12 gal. of stirred acetone. soft cake was milled repeatedlyin a W-P mill with fresh acetone. at room temperature under a constantly applied mechanical pump vacuum. The yield was 45 1 g. Analysisof the product indicated a content (combined vinyl acid succinate) of 29.7 mole percent.

' In a similar fashion other acid derivatives of poly- 0 vinyl half esters of the other acids-mentioned in the foregoing section have been prepared.

The dope was then poured. into approxl The p The polymer was then dried in a vacuum oven EXAMPLE 3. coroLY vrrtYL ALCOHOL-VINYL EXAMPLE 5.COPOLY(VINYL ALCOHOL-VINYL ACID DIGLYCOLATE) In a 300 ml. three-necked flask equipped with a reflux condenser, stirrer and thermometer were placed 110 ml. of dimethylforrnamide and 22 g. of low viscosity polyvinyl alcohol which is essentially completely hydrolized. The stirred suspension was heated to 135 C. on a Glas- Col mantle to obtain a clear, light amber dope. To this at 145 C. was added 20.3 g. of diglycolic anhydride. After heating for 4 hour at. 142l45 C., the dope was cooled and poured into stirred acetone. The product which precipitated was washed several times in fresh acetone and dried at room temperature in a desiccator under a constantly applied water pump vacuum. The yield of rubbery polymer was 34 g. Analysis of the product indicated a content of 20.8 mole percent of combined vinyl acid diglycolate.

I The procedure in Example 1 is used to get the copolymer into. solution.

EXAMPLE 6.COPOLY(VINYL ALCOHOL-VINYL ACID GLUTARATE) In a 300 ml. three-necked flask equipped with a reflux condenser, thermometer and stirrer were placed 110 ml. dimethylformamide and 22 g. of low viscosity polyvinyl alcohol which is essentially completely hydrolyzed. The suspension was heated on a Glas-Col mantle with stirring to 135 C. to obtain a clear light amber dope. To this, at 145 C., was added 17.1 g. of glutaric anhydn'de. After heating for hour at l45-149 C., the dope'was diluted with 40 ml. dimethylformamide' and was poured, in a fine stream, into stirred acetone. The product which precipitated was washed several times in fresh acetone and dried at room temperature in a desiccator under a constantly applied water pump vacuum. The yield of light yellow rubbery polymer was 27.5 g. Analysis of the product indicated a content of 21.5 mole percent of combined vinyl acid glutarate.

The procedure in Example 1 was used to get the copolymer into solution.

EXAMPLE 7.COPOLY(VINYL ALCOHOL-VINY L CARBOXY METHYL ETHER) In a 300 ml. three-necked flask equipped with a reflux condenser, thermometer and stirrer were placed. 110 ml. dimethylformamide and 22 g. of low viscosity polyvinyl alcohol which is essentially completely hydrolized. The

stirred suspension was heated to 135 C. on a Glas-Col mantle to obtain a clear amber dope. To this, at 145 C., was added a solution of 33 g. chloroacetic acid in70 ml. dirnethylformarnide which had previously been heated to approximately 90 C. The solution was heated for 4 hour at 150- -152 C. The cooled dope was poured into stirred acetone to precipitate a yellow colored polymer which was Washed several times in fresh acetone and dried at room temperature in a desiccator under a constantly applied water pump vacuum. The yield of light yellow polymer was 22.5 g. Analysis ofthe product indicated a content of 8.35 mole percent of combined vinyl carboxymethyl ether. e

The procedure in Example 1 is used to get the copolymer into solution.

The photographic emulsions containing the half esters of polyvinyl alcohol indicated above are illustrated in the following examples:

Samples of a coarse-grained gelatino-bromoiodide emulsion containing normal emulsion addenda, e.g., spreading agents, hardeners,'etc., containing 178 g. gelatin per mole of silver and in addition 45 g. of the following polyvinyl half esters of polyvinyl alcohol per mole of silver was coated on a suitable film support. A fresh strip of each coating was exposed in an Eastman Ib sensitometer, developed for three minutes in Kodak Dl9b Developer, fixed, washed and dried.

Thephotographic improvement obtained in each case is shown in the following table: 1

Table IV Description Rel. 'y Fog Max.

Speed Density Control 100 1. 30 0. 05 1. 53 Control-{-45 g. cmpd. No. 6 per Ag mole 115 2. 00 0.05 1. 80 Control-l-45 g. cmpd. N0. 7 per Ag mole. 138 1. 89 0.05 1. 76 Control 100 l. 58 0.06 1. 40 Control+ g. cmpd. No. 8 per Ag mole. 141 2. 68 0.06 1. 48

The photographic emulsions containing the half esters of polyvinyl alcohol'of our invention are further illustrated in the following examples:

A coarse-grained gelatin-silver bromoiodide emulsion containing the normal emulsion addenda, e.g., coating aids, hardeners, etc., and 178 g. gelatin per mole of silver halide was coated with and without 43 g. of the following succinoylated polyvinyl alcohol per mole of silver. A

fresh strip of each coating was exposed in an Eastman lb sensitometer, developed for 3 minutes in Kodak D19b Developer, fixed, washed and dried.

The photographic improvement obtained is shown in the following table:

acid in accordance with our invention are added to the gelatin composition or to a photographic emulsion in a proportion Within the range of up to 30% of the total colloid present. The preferred range of the polyvinyl alcohol half ester of dicarboxylic acid is between 20 and 30% depending on the increase in density desired. Levels of polyvinyl alcohol half ester of dicarboxylic acid substantially above 30% of the total colloid present in a layer causes troublesome problems such as undesirable viscosity increase and haze or opalescence in the coating when it is dried down.

The photographic emulsions used in practicing our invention are of the developing-out type.

Table III HALF ESTERS OF POLYWINYL ALCOHOL) Mole Percent PVA DMF Anhydride Yield Reaction Cmpd. No. Acid Ester (g.) (ml.) (g.) (g.) Solubility Cale. Found 33 165 8.55 33 10 7.7 Water/rt? 22 17. 1 27.5 30 21. 5 Do.* 660 3,300 525 848. 35 23.6 Water+Alkali.

Room temperature.

1,574,944, issued-March 2, 1926, Sheppard et-al. U.S.

Patent 1,623,499, issued April 5, 1927, and Sheppard et all U;S. Patent 2,410,689, issued November 5, 1946.

' The emulsions can also be treated Withsalts of the noble metals such as ruthenium, rhodi'um,,palladium, i'rid ium and platinum. Representative compounds are ammonium chloropalladate, potassium chloroplatinate and a sodium chloropalladite, which are used' for sensitizing in amounts "below that which produces any substantial fog inhibition, as described in Smith and Trivelli US. Patent 2,448,060, issued August 31, 1948, and as anti-foggants in higher amounts, as described in Trivelli and Smith US...

Patents 2,566,245, issued August 28, 1951, and 2,566,263,

issued August 28, 1951.

The emulsions can also be chemically sensitized with A gold salts as described in Waller etal. US. Patent 2,399,-

soluble salts (Lowe and Jones U.S..Patent 2,521,926, is-' sued September 12, 1950).

The emulsions can also be optically sensitized' with 'cyanine and merocyanine dyes, such as those described in Brooker US. Patents 1,846,301, issued February 23,

1932; 1,846,302, issued February 23, 1932; and 1,942,854,

issued January 9, 1934; White US. Patent 1,990,507, is sued February 12, 1935 aBrooker and White US. Patents 2,112,140, issued March 22, 1938; 2,165,338, issued July -11, 1939; 2,493,747, issued January 10, 1950, and 2,739;

964, issued March 27, 1956; Brooker and Keyes US. Patent 2,493,748, issued January 10, 1950; Sprague US. Patents 2,503,776, issued April 11, 1950, and 2,519,001, is

sued August 15, 1950; Heseltine and Brooker US. Patent 2,666,761, issued January 19, 1954; Heseltine US. Patent 2,734,900, issued February 14, 1956; VanLare US. Patent 2,739,149, issued March 20, 1956; and Kodak Limited British Patent 450,958, accepted July 15, 1936.

The emulsions can also be stabilized with the mercury compounds of Allen, Byers and Murray US. Patent 2,728,663 issued December 27, 1955; Carrolland Murray US. Patent, 2,728,664, issued December 27, 1955; and Leubner and Murray US. Patent 2,728,665, issued December 27, 1955; or with gold salts as described in Damschroder US. Patent 2,597,856, issued May 27, 1952,;and Yutzy and Lcermakers US. Patent 2,597,915, issued May 27, 1952; the triazo1esofHeimbach and Kelly US. Patent- 2,444,608, issued July 6, 1948; the azaindenes of Heimbach and Kelly US. Patents 2,444,605, and 2,444,606,

issued July 6, 1948; Heirnbach US. Patents 2,444,607,

issued July 6, 1948, and 2,450,397, issued September 28, 1948; Heimbach and Clark US. Patent 2,444,609, issued July 6, 1948; Allen and Reynolds US. Patents 2,713,541, issued July 19, 1955, and 2,743,181, issued April 24, 1956; Carroll and Beach US. Patent 2,716,062, issued August 23, 1955; Allen and Beilfuss US. Patent 2,735,769, issued February 21, 1956; Reynolds and Sagal U.S. Patent 2,756,147, issued July 24, 1956; Allenand Sagura U.S. Patent 2,772,164, issued November 27, 1956, and those disclosed by Birr in Z. wiss. Phoh, vol. 47, 1952, pages 228; the disulfides of Kodak Belgian Patent 569,317, issued July 31, 1958; the quaternary benzothiazolium compounds of Brooker and Stand US. Patent 2,131,038, is-

suedSeptember 27, 1938, or the polymethylene bisbenzo thiazolium salts of Allen-and. Wilson US. Patent 2,694,- 716, issued -November; 16,1954; the zinc and cadmium salts of Jones US. Patent 2,839,405, issued June 17, 1958; and the carboxymethylmercapto compounds of Murray, Reynolds and Van Allan -U.S.- Patent 2,819,965, issued January 14, 1958.

The emulsions may al'soicontain speed increasing com pounds of the quaternary ammonium type of Carroll US. Patent 2,271,623, issued February 3; 1942;, Carroll and Allen US. Patent 2,288,226, issuedJunej30, 11942; and Carroll, and Spence U.S. Patent 2,334,864; issued November 23, 1943; or the polyethylene glycol type of Carroll and Beach U.S. Patent 2,708,162, issued May 10,

1955 or the quaternary ammonium salts and polyethylene glycols. of. Piper US. Patent 2,886,437, issued May 12, 1959; as Well as the thiopolymersfof Graharnand Sagal US. patent application Serial No. 779,839, filed December 12, 1958, and the Dann and ChechakUS. application Serial No. 779,874, filed December 12, 1958.

The'emulsions may contain a suitable'gelatin plasticizer such as glycerin; a dihydroxy alkane such asv 1,5-pentane diol as described in, Milton and Murray US. application Serial No. 588,951, filed June 4, 1956; an ester ofan ethylene bis-glycolic acid 7 such as ethylene bis(methyl glycolate) as described in Milton US. application Serial No. 662,564,,filed May 31', 1957; bis(ethoxy diethylene glycol) succinate as described in, Gray U.S.,afpplication Serial No. 604,333, filed'August 16, 1956, or a polymeric hydrosol' as .resultsfrom the emulsion polymerization of a mixture of an amide of' an acidof the acrylic acid series, an acrylic acid ester and astyrene-type compound as described in Tong US. Patent 2,852,386, issued September 16, 1958. The plasticizer may be added to the emulsion beforeor after the addition of a sensitizing dye, if used. 7 i J The emulsions may be hardened with any suitable hardener for gelatin such as formaldehyde; a halogensubstituted aliphatic acid such as'mucobrornic' acid as described in White US. Patent 2,080,019, issued May 11, 1937; a compoundhaving a plurality of acid anhydride groups such as 7,8-diphenylbicyclo (2,2,2)-7- octene-2,3,5,6-tetracarboxylic dianhydridep or a .dicarboxylic or-a disulfonic acid chloridesuchas:terephthaloyl chloride as described in Allen andCarroll US. Patents 2,725,294, and 2,725,295, both issued November 29, 1955 acyclic 1,2-diketone such as cyclopentane-1,2-dione as described in Allen and. Byers US. Patent 2,725,305, issued November 29, 1955 a bie ster of methanesulfonic acid such as 1,2-di-(methane-sulfonoxy) ethane as described in Allen and LaaksofU S. Patent 2,726,162, issued December 6, 1955; 1,3-dihydroxymethylbenzimidazol-Z- one as describedinJuly, Knott and PollalcUS. Patent. 2,732,316, issued January 24, 1956; a dialdehyde or a sodium bisulfite derivative thereof such as ,B-methyl glutaraldehyde bis-sodium bisulfite as described in Allen and Burness US. patentapplicationSerial No. 556,031,'filed December 29, 1955; a bis aziridine carboxamide such as trimethylene bis(1-aziridine carboxamide) asde scribed in Allen and Webster US patent application Serial No.

599,891, filed July 25, 1-956; 2,3-dihydroxydioxane as described in Jetfreys US. Patent 2,870,013,, issued January 20, 1959; or bisisocyanate as described in Henn et al. US. patent application Serial No. 805,357, filed April 10, 1959. i

The emulsions may contain a. coating aid *such as saponin; a lauryl or oleoyl monoether of polyethylene glycol as described in Knox and Davis US; Patent 2,831,766, issued April 22, 1958; a salt of a sulfated and alkylated polyethylene glycol ether as described in Knox and Davis US. Patent 2,719,087, issued September 27, 1955; an acylated alkyl taurine such as the sodium salt of N-ole oyl-N-methyl taurine as described in Knox,

.Twardokus and DavisuU.S.'-Patent 2,739,891, issued March 27,1956; the reaction product of a dianhydride of tetracarboxybutane with an alcohol or an aliphatic amine containing from 8 to 18 carbon atoms which is treated with a base, for example, the sodium salt of the monoester of tetracarboxybutane as described in Knox, Stenberg and Wilson U.S. Patent 2,843,487, issued July 15, 1958; a water soluble maleopimarate as described in Knox and Fowler U.S. Patent 2,823,123, issued February 11, 1958; an alkali metal salt of a substituted amino acid such as disodium N-(carbo-p-tert. octyl-phenoxy- 'pentaethoxy)-glutamate as described in Knox and Wilson U.S. patent application Serial No. 600,679, filed July 30, 1956; or a sulfosuccinamate such as tetrasodium N-(1,2- dicarboxyethyl)-N-octadecyl sulfosuccinamate as described in Knox and Stenberg U.S. patent application Serial No. 691,125, filed October 21, 1957, or a sodium salt of an alkylarylpolyether sulfonate of U.S. patent application Serial No. 753,642, filed August 7, 1958.

The addenda which we have described may be used in various kinds of photographic emulsions. In addition to being useful in X-ray and other nonoptically sensitized emulsions they may also be used in orthochromatic, panchromatic, and infrared sensitive emulsions. They may be added to the emulsion before or after any sensitizing dyes which are used. Various silver salts may be used as the sensitive salt such as silver bromide, silver iodide, silver chloride, or mixed silver halides such as silver chlorobromide or silver bromoiodide. These agents can also be used in emulsions which form latent images predominantly on the surface of the silver halide crystal or in emulsions which form latent images predominantly inside the silver halide crystal, such as those described in Davey and Knott U.S. Patent 2,592,250, issued April 8, 1952.

We claim:

1. A gelatin-silver halide photographic emulsion of good density properties containing about 10-30%, based on the weight of the gelatin, of a saturated aliphatic dicarboxylic acid half ester of polyvinyl alcohol, said acid having a carbon chain length of 4-7 carbon atoms.

2. A gelatin-silver halide photographic emulsion of good density properties containing about 10-30%, based on the weight of the gelatin, of the succinic acid half ester of polyvinyl alcohol.

3. A gelatin-silver halide photographic emulsion of good density properties containing about 10-30%, based on the Weight of the gelatin, of the glutaric acid half ester of polyvinyl alcohol.

4. A gelatin-silver halide photographic emulsion of good density properties containing about 10-30%, based on the weight of the gelatin, of the adipic acid half ester of polyvinyl alcohol.

5. A photographic element comprising a support containing thereon a layer of a gelatin-silver halide photographic emulsion containing about 1030%, based on the weight of the gelatin, of a saturated aliphatic dicarboxylic acid half ester of polyvinyl alcohol, said acid having a carbon chain length of 4-7 carbon atoms.

6. A photographic element comprising a support having thereon a photosensitive layer of a gelatin-silver halide photographic emulsion containing about 10-30%, based on the weight of the gelatin, of the succinic acid half ester of polyvinyl alcohol.

7. A photographic element comprising a support having thereon a photosensiitve layer of a gelatin-silver halide photographic emulsion containing about l030%, based on the weight of the gelatin, of the glutaric acid half ester of polyvinyl alcohol.

8. A photographic element comprising a support having thereon a photoensitive layer of a gelatin-silver halide photographic emulsion containing about 1030%, based on the weight of the gelatin, of the adipic acid half ester of polyvinyl alcohol. g a

References Cited in the file of this patent 1 UNITED STATES PATENTS 2,828,289 Mench Mar. 25, 1958 2,882,161 Dann et al Apr. 14, 1959 3,000,741 De Pauw et a1 Sept. 19, 1961 

1. A GELATIN-SILVER HALIDE PHOTOGRAPHIC EMULSION OF GOOD DENSITY PROPERTIES CONTAINING ABOUT 10-30%, BASED ON THE WEIGHT OF THE GELATIN, OF A SATURATED ALIPHATIC DICARBOXYLIC ACID HALF ESTER OF POLYVINYL ALCOHOL, SAID ACID HAVING A CARBON CHAIN LENGTH OF 4-7 CARBON ATOMS. 